First step should be deporting any illegal who has committed any crime while in the US. If caught returning, mandatory 5 year prison sentence. Any illegal who has interaction with any law enforcement agency and for whom no record of entry can be found (got always) will be deported immediately. Any municipality declining to cooperate with Federal immigration angencies will lose anll Federal funding and will be disqualified from participating in any Federal surplus equipment programs. Anyone caught using a fraudulent Social Security number or false identity for employment will be immediately deported. Employers who hire undocumented workers must report them and pay a Federal tax, failure to report will result in a punitive fine equal to or greater than five years of the proposed tax amount.
Phase 2 - every illegal alien who has entered the United States within the last four years either self deports within an established timeframe or petition for expedited asylum hearing (hire more immigration judges). Asylum seekers (with certain exceptions) must relocate to Mexico, Canada or another country while awaiting their hearings.
Phase 3 - long term illegals, must establish a bonafide reason for remaining in the United States (e.g. they have properly applied for US citizenship prior to January 20, 2020, they have an legitimate employment record, they have served in the US military, they have children who are US citizens, they own a home in the United States, they have a legal business in the United States). These people may argue with some merit that they have established solid ties in the US and are productive.